Testosterone (T) is a molecule that originates in the same sexual organs in both men and women but circulates in different amounts. Women have one tenth the amount of testosterone as compared to men but by age forty, their level can rise to half that of a 20 year-old man. It seems somewhat paradoxical that women’s testosterone goes up as they age and men’s goes down. But maybe that’s why women live longer!

Although men make greater amounts of T than women, the hormone is essential for the survival of all animals. When testosterone falls below vital levels, both sexes suffer diminished memory, difficulty orienting in space or bumping into things, plus a lagging sexual desire. Most people consider these problems as a normal part of the aging process.

Testosterone boosts strength and decreases body fat. In tiny amounts, it accomplishes the same effect in men as well as women. In other words, testosterone is a very versatile hormone. It can convert to either estrogen or dihydrotestosterone (DHT). As testosterone strengthens our bodies and improves our memory, it also creates that essential sense of well-being that makes us all feel wonderful and alive regardless of our age. The value of this effect is immeasurable!

This benefit allows men to improve their physique as long as they consume adequate protein and limit their fat intake while taking part in an intensse regimen. Women can accomplish the same goals, if their T levels are pushed into the normal physiologic range for their age group. As women age, they too need testosterone to help them control their weight. Men can exercise less than women while still increasing their lean body mass since they have higher levels of testosterone and can pack on muscle naturally.

However, it's very important to understand that too much testosterone can be harmful. As women acquire excess abdominal fat, their estrogen levels rise along with their SHBG and their free testosterone (FT) also increases. . Despite the fact that most of the estrogen in either a man or a woman comes from testosterone, both have directly opposite effects in the other sex. Sex steroids have potent but different effects in men and women. Apparently this gender distinction is also found in the hormones that cause obesity and diabetes.

There are significant but practical obstacles to precise testosterone supplementation in women. This is partly for obvious reasons; whereas men make testosterone in their testicles, testosterone production in women is divided between the adrenal glands and their ovaries. The precursor hormones, DHEA and androstenedione, convert into about 50 percent of the necessary female testosterone away from her ovaries. In some women, particularly as they grow older, these conversions do not occur and they may end up running low in testosterone when their ovaries fail.

Other women may have plenty of testosterone as they age, remaining vibrant and strong. Strong women have very high testosterone levels, often approaching male levels after menopause. Doctor Lorraine Dennerstein, from Melbourne , concluded from her studies that the primary drivers for a woman's libido are her androgens, the male hormones, testosterone and its metabolite dihydrotestosterone.

The rise in free testosterone in women not only masculinizes them, but it can result in a decrease in adiponectin, the good hormone that is released from their fat cells. Adiponectin improves insulin sensitivity and may increase lifespan for women. On the other hand leptin, which aggravates insulin resistance, also rises as FT increases in women. So women are prone to diabetes and increased breast cancer and risk of heart disease as they get fatter.

For women, testosterone has the power to decrease fat mass, but it can also promote insulin resistance, whereas in men, it increases lean body mass and decreases insulin resistance. In women, testosterone increases vaginal lubrication in the same way that it increases nitric oxide in men's arteries, allowing their penis to become erect.

Low testosterone has powerful effects on the human brain creating marked variation between men and women. Earlier I only mentioned a few of the numerous problems caused by a malfunctioning hormone system. The most distressing include memory loss, decreased libido, fatigue, loss of height, increased weight, combined with depression and diabetes.

In any case, hormones may lie at the core of some of our most universal conditions. Although the same hormones are present in both sexes, they affect the genders in dissimilar ways. Men may have problems with obesity more often than women, yet women become more obese more easily. Women have depression more often than men, but depressed men are more likely to commit suicide. Women have immune disorders twice as frequently, but usually survive longer despite these circumstances.

Women also suffer from testosterone deficiency just before menopause, while men develop this condition after andropause. It is intriguing to note that after menopause, women usually have higher testosterone than men of the same age. Men experience a drop in their immune function when their testosterone levels fade away with aging.

Most doctors shy away from treating authentic hypogonadal patients for fear of being labeled as steroid providers. Andropause is not considered a legitimate medical diagnosis in the United States despite the fact that Canada covers the treatment of partial androgen deficiency of aging men (PADAM) on their insurance program. Testosterone undecanoate, a long lasting injectable testosterone is being tested as a quarterly injectable supplement, but this form of testosterone is not available in this country.

Consideration of hormonal deficiency is a critical part of the medical evaluation of any patient with sexual dysfunction, memory problems or low libido. Lately studies have confirmed that testosterone may even help prevent Alzheimer's dementia and is essential for normal human brain function.

Yet currently testosterone replacement therapy or TRT is only offered as a treatment for HIV patients, AIDS or Cancer and Hypogonadism, if levels are below 300 ng/dl. A testosterone supplement for women does not exist in the year 2006, while HRT, the standard for replacement of female hormones for the past three decades, is being questioned as to its long-term safety.

Based on a considerable amount of scientific data, we now believe that testosterone modifies brain structures early in life, particularly the hippocampus , that part of the brain that is responsible for memory in humans. Moreover it's not only your husbands or sons who may experience the deficiency symptoms of sleep problems, increased appetite, snoring and a diminished sexual arousal. Your daughters or wives can also fall into this pattern as they gain weight. With the weight-induced decline in testosterone, as men lose their morning erections, women notice a lack of interest in any physical contact—including cuddling and kissing.

If you lack a full, satisfying sexual relationship, you are not alone. If you consider the estimated 30 million men with erectile dysfunction plus the estimated 40 million women suffering some degree of sexual dysfunction, we are talking about one third of the American population. In 2003 according to the Massachusetts Male Aging Study, 52 percent of men over the age of 40 had some degree of erectile failure. Several female physicians: Susan Raiko, Jeanne Alexander, Lorraine Dennerstein, Jennifer and Laura Berman, Lisa Tenover, Adrian Dobs and Susan Davis have published their writings and research regarding the role of male hormones in women's sexual function.

Many of the effects of low testosterone are troublesome but not often serious enough to make the person seek help. The less common effects include an inability to concentrate, diminished interest in daily activities, sleep disturbances, irritability, “grumpy old man syndrome” and depressed moods. This description probably fits a lot of sixty plus men and a few women. But it's a big mistake to let your husbands' testosterone levels drop so low that they begin experiencing even mild symptoms such as these. Women experience these identical effects when their estrogen levels drop.

Regrettably, few men or women bother to find out what their normal testosterone levels are before they have a problem. Even if a person knows how much testosterone is circulating in their body, optimal levels vary so widely from one man or women to another that accurate treatment to adjust these levels is tricky but not impossible. Don't ignore warning signs of a hormonal dysfunction that can be easily corrected if diagnosed early. Men and women need to start being proactive when it comes to their hormone function. It is not normal to lose your mind or memory when you get older. Old age is not associated with feeling irritable all the time. Nor is it normal for your joints to become stiff and painful as you age. Are these due entirely to hormonal shortage?

Two hormones, testosterone and DHEA, jointly regulate the fluid in your joints and keep your tendons and ligaments operating smoothly. Support for this observation comes from studies of youngsters with arthritis who have been found to possess abnormally low levels of testosterone in their joint fluid. Older people with aches and pains in joints and ligaments that improve with exercise may be deficient in testosterone.

Testosterone helps our body rapidly heal the tissues surrounding our joints. Testosterone is also increased in response to moderate exercise, which sort of lubricates your joints. Future studies may show that testosterone deficiency might lead to arthritis and treatment may help improve symptoms of pain and stiffness. In this regard, I am merely making an observation and not advocating an alternative use for testosterone therapy in arthritis.

While women have about one tenth the amount of testosterone found in men, this hormone plays a vital role in a woman's “ability to be aroused... and in her appetite for being sexual,” according to Dr. Rosemary Basson, with the Center for Sexuality, Gender Identity and Reproductive Health in British Columbia. Dr. Basson points out that testosterone plays significant roles in women. These include promoting bone growth, increasing bone density, stimulating the production of red blood cells, promoting muscular development, plus improving moods and sex drive. Testosterone may also lower total cholesterol and LDL and decrease insulin resistance.

A woman with high testosterone is the owner of a lean body with a flat strong abdomen and high energy. She can be sexually aggressive and especially attractive but is not at all masculine. Testosterone (T) nurtures sexual desire and heightens a woman's sensitivity to sexual stimulation. The result is a deeper sense of physical gratification during sexual intercourse. These subtle feelings and sexual dreams are missing in women with low T levels.

In Listen To Your Hormones, I review the basics of the endocrine system and how it responds to progesterone, estrogen and testosterone. In the brain, testosterone (T) converts to estrogen (E), creating new brain cells or neurons. Dihydrotestosterone (DHT) peaks our human sexual drive. In general, testosterone enhances libido and energy in women hitting the highest point just before ovulation. Yet the Endocrine society states there is no benefit to women by raising their testosterone.

The first indication that a woman may have a low T level is usually a lack of sexual desire and erotic thoughts or dreams. An article concerning women who were deficient in testosterone appeared in the February 2005 issue of Endocrine News. The main point made by Dr. Glenn Braunstein, of the UCLA School of Medicine, was that women have been receiving various types of testosterone supplementation to treat the loss of sexual responsiveness for over 50 years, yet its effectiveness for libido has never been properly investigated. 

Currently there are no FDA-approved testosterone treatments for women. Nonetheless, testosterone has been used clinically in women for decades. A number of different products are presently in use for men, including oral methyl testosterone, associated with liver toxicity, besides T-gels, injections and implants. Any woman with a loss of sexual desire due to removal of her ovaries (the major production center of testosterone) feels remarkably better when testosterone is replaced. This is called an “anecdotal response” implying it has not been adequately tested.

Subsequently, most women have been forced to use T products made for men. The irony is that the testosterone products marketed for a man are strong enough for a woman when used in tiny amounts. At this point in time, many men do not use the products made for them, while women are deprived of the appropriate therapy. It seems ironic that a half a gram of a one percent testosterone gel, made for men, is adequate hormone replacement for a postmenopausal woman. But new treatments are on the horizon with T-gel coming from BioSante Labs and a new testosterone patch from the other side of the world.

For a second time, it is interesting to observe that inclusive of the year 2006, no product exists for testosterone therapy for women. Over the past three years, Susan Davis, an expert in female hormone therapy, has successfully tested Intrinsa®, a transdermal T patch for women on hundreds of women in Melbourne , Australia . Late in 2004, a panel of advisers, from a competing pharmaceutical company, BioSante, told the FDA that in light of the possible risks for heart disease and stroke, more research was needed before Intrinsa® should be approved. Another few years of research were suggested and the FDA went along with the recommendations.

Just as it does in men, testosterone therapy helps to heighten sexual desire in women. Women derive half of their testosterone from their ovaries and half from their adrenal glands. Their T levels peak between the age of 20 and 30, diminish by about 50 percent after menopause, but never disappear completely. It is interesting to note that some postmenopausal women notice an increase in testosterone as they age.

Menopause should not be considered a disease but an accepted transition in women from fertility to cessation of menstruation. Many women find menopause to be a positive experience since they no longer have to worry about pregnancy and can enjoy luxurious sex in the morning without interruption from children or carpools. Weight gain is common but is not a part of the menopause. As Dr. Patricia Allen, author of Staying Married… and Loving It, stated on a recent TV interview Embracing Menopause , “Hormones do not make you fat, it is what you eat that makes you fat”. This is true but difficult for many people to accept. However, many postmenopausal women complain of a decreased desire to exercise, which could contribute to weight gain after menopause. 

Less than a milligram a day of a testosterone supplement, seems to improve sexual health in testosterone deficient women without bringing on any masculine traits. The testosterone doses used by doctor Davis have ranged from 350 to 500 micrograms. Menopausal women appear to benefit from testosterone with increased energy, loss of body fat and an improved sense of well-being. They do however develop more insulin resistance, as I mentioned previously.

Women with low T levels can suffer from symptoms that are similar to those experienced by men, including lowered libido and decreased ability to achieve sexual arousal. If that wasn't bad enough, if we add fatigue and negative moods, it's no wonder they have trouble living together. Studies examining testosterone replacement therapy (TRT) in women have been few, as a consequence further study is clearly necessary to establish the validity of TRT in women.

Studies have shown that testosterone (T) may increase a postmenopausal woman's lean body mass but it may also increase her insulin resistance. The complete opposite effect occurs in men, for whom testosterone lowers insulin resistance. T lowers HDL, the good cholesterol, while increasing lean body mass in men. Estrogen in both men and women raises the good cholesterol while lowering the bad. At the same estrogen helps lower cholesterol, it has an opposite effect of increasing fat mass in both sexes. It is for these reasons that appropriate age sensitive levels have been established. Just as with men, women need treatment for their male hormones, too.

Eventually age drives most women's testosterone down as predictably as it does in men. As testosterone levels drop, previously youthful women begin aging rapidly, often becoming overweight and more passive. Women with low T feel tired and lazy and gain weight easily. Women with low T develop heart disease sooner and lose their memory faster than women with normal levels.

Aging is not the only cause for the dwindling of women's androgen levels. Medications including the use of birth control pills and the use of a popular class of antidepressants–– serotonin re-uptake inhibitors or SRIs. Prozac®, Paxil®, Zoloft® and Lexapro® are four common SRIs that have been shown to cause a decreased libido, as well as an inability to reach orgasm. It is interesting to note that the same effect of anorgasmia takes the form of delayed ejaculation in men.

The answers are not in on what is the optimum amount of testosterone to give a woman. It is clear that as we humans mature, we should not accept obesity as the norm. Vitality, vim and vigor and permanent weight loss are attainable with enough testosterone, exercise and a healthy diet.

Sieminska L , et al. [Sex hormones and adipocytokines in postmenopausal women] [Article in Polish] Pol Merkuriusz Lek. 2006 Jun;20(120):727-30. lusiem@poczta.onet.pl

Visceral fat accumulation occuring in postmenopausal women is connected with hypoestrogenism, decreased production of sex-hormone binding globuline (SHBG) and with rise in free testosterone. They have been identified as risk factors for cardiovascular diseases. The exact mechanisms mediating relationships between the excess of visceral adiposity, hormonal variations after menopause and metabolic disturbances, remain unknown. We speculate that adipocytokines produced by adipose tissue: adiponectin, leptin and resistin, might play a role. Adiponectin is a hormone which plays a role in insulin sensitivity and lipid oxidation, and possesses anti-inflammatory properties. Increased levels of androgens post menopause and low SHBG are connected with decreased production of adiponectin. Leptin is another of the adipocytokines which has been shown to be linked to insulin resistance, increased pressure and hypertriglyceridaemia. Sex steroids have effect on leptin secretion but the associations between leptin and menopause are controversial. Recently it was found that resistin, another bioactive substance produced by adipose tissue may related to insulin resistance. Studies on animals indicate that ovariectomy and testosterone significantly increased resistin expression. It seems that adipocytokines may be a link connecting postmenopasual hormonal changes, the excess of visceral fat and increased risk of cardiovascular diseases.

Zang H, et al. EFFECTS OF TREATMENT WITH TESTOSTERONE ALONE OR IN COMBINATION WITH ESTROGEN ON INSULIN SENSITIVITY IN POSTMENOPAUSAL WOMEN. Fertil Steril. 2006 Jul;86(1):136-44. Epub 2006 Jun 5. Little is known about metabolic effects of testosterone treatment in postmenopausal women. The aim of the study was to compare the treatment effects of testosterone, estrogen, and testosterone plus estrogen on insulin sensitivities, body compositions, and lipid profiles in healthy postmenopausal women. DESIGN: An open, randomized clinical study with parallel group comparison. SETTING: Women's health clinical research unit at a university hospital. PATIENT(S): Sixty-three naturally postmenopausal women participated in the study. INTERVENTION(S): The participants were randomly assigned to 3 months of treatment with testosterone undecanoate (40 mg every second day), estradiol valerate (2 mg daily), or the combination of both. MAIN OUTCOME MEASURE(S): Insulin sensitivity assessed by euglycemic hyperinsulinemic clamp, body composition, and serum lipids. RESULT(S): Insulin-induced glucose disposal was reduced by approximately 20% after treatment with testosterone alone, and after the combined treatment, but not by estrogen alone. Body weight, but not total body fat, increased significantly by about 1 kg in all groups. Lean body mass was significantly increased in the group of combined treatment and tended to be increased by testosterone alone. High-density lipoprotein (HDL)-cholesterol decreased significantly by testosterone treatment. In contrast, HDL-cholesterol increased, whereas low-density lipoprotein (LDL)-cholesterol and lipoprotein-(a) [Lp(a)] decreased with estradiol treatment. CONCLUSION(S): We conclude that 3 months of treatment with testosterone undecanoate in postmenopausal women induces insulin resistance and an adverse serum lipid profile but may increase lean body mass.